Known valves of this type include a tubular body in which a valve stem moves axially, the head whereof is provided or not with a sealing lining suitable for cooperating, in a sealed manner, with a corresponding seat of the valve body, the stem acting depending on a predetermined pressure, against a coiled spring housed in a chamber coaxial with the tubular body and disposed between a bearing zone with respect to it and the stem, to return the latter to the seat with a predetermined force.
For proper operation of these valves, it is necessary to provide for a certain number of functions: radial guidance of the valve head; initial sealing and sealing during re-closure; an optimized flow area; repeatability of the axial position of the valve head with the connector tappet in the case of charging valves; the possibility of adjusting the initial compression of the spring, in the case of pressure regulators, of overpressure valves and of differential valves; stoppage of translation by an abutment in the case of valves, of pressure regulators, of differential valves.
In the prior art, these functions are traditionally provided by the addition of a mechanism screwed, press fitted or clipped at the back of the valve.
When a defined opening pressure is to be satisfied, as is the case with overpressure valves, a screw, a nut, or a fitted ring allow the force of the spring to be adjusted.
This has the major disadvantage of complicating assembly by multiplying the number of parts constituting the valve.